Calcined mesoporous Sn-TiO2 as a lithium-ion battery anode

Abstract

Titanium(IV) oxide (TiO₂) is a promising alternative to graphite anodes used in Li-ion batteries (LIBs) due to its low toxicity and small volume change during cycling. SnO₂ has a higher specific capacity than TiO₂ but suffers from large volume changes during charging-discharging. Accordingly, doping of TiO₂ with Sn can provide higher Li-ion storage capacity, while maintaining the advantages of TiO₂. Here, a mesoporous Sn-doped TiO₂ with high surface area (up to 259 m²/g) is synthesized using an inverse micelle sol-gel method followed by varying the calcination temperature. Crystallographic studies showed successful Sn doping. The electrochemical performance of the synthesized materials was evaluated by constructing a lithium-ion half-cell battery and all the batteries were cycled at both constant and variable charge rates. The 8 % Sn doped TiO₂ calcined at 350℃ had the highest 340 mAh/g specific capacity which is twice that of the same amount of Sn-doped sample calcined at 250℃. There is a correlation between increased Li-ion storage capacity of the calcined mesoporous samples and the porosity and oxidation state of the constituent ions. The intent of this study is to show the importance of optimizing calcination temperature that may result in improved electrochemical performance of Li-ion batteries with similar anode materials, not necessarily to outperform the existing Sn-doped TiO₂ samples.